Wells’ Criteria for Pulmonary Embolism is a clinical decision-making tool developed to estimate the probability of PE in patients with suspected venous thromboembolism. Created by Dr. Philip Wells and colleagues in the late 1990s, it incorporates both objective findings and clinical judgment, such as signs of deep vein thrombosis, recent immobilization, heart rate, hemoptysis, and history of cancer. A key feature of the score is the inclusion of whether an alternative diagnosis is less likely than PE, which reflects the clinician’s gestalt.

The score stratifies patients into probability categories: low, intermediate, and highor into a simplified two-tier model of “PE unlikely” versus “PE likely.” This stratification helps guide diagnostic strategies. For example, in patients with a low Wells’ score and a negative D-dimer, PE can often be ruled out without the need for imaging. In patients with a higher score, confirmatory imaging such as CT pulmonary angiography or ventilation-perfusion scanning is recommended.

Wells’ Criteria has become a central part of diagnostic algorithms worldwide due to its simplicity, reproducibility, and evidence base. It helps reduce unnecessary imaging in low-risk patients, minimizes radiation and contrast exposure, and ensures high-risk patients undergo timely evaluation. Studies and systematic reviews have validated its accuracy, especially when combined with D-dimer testing.